Neck

LARYNX

Discuss the anatomy of the pharyngeal constrictors (10 marks)

DESCRIPTION

• Three overlapping constrictors arranged in posteriorly ascending fibers
• All insert into midline pharyngeal raphe (attaches to pharyngeal tubercle)
• Serial constriction of pharynx during swallow; elevate larynx & hyoid bone
• Longitudinal muscles (palatopharyngeus, salpingopharyngeus, stylopharyngeus) not included

SUPERIOR CONSTRICTOR

• Superior free edge bordered by pharyngobasilar fascia / Passavant’s ridge
• Described in parts based on origin
  • pterygopharyngeus (lower posterior border medial pterygoid plate)
  • buccopharyngeus (pterygopharyngeal raphe)
  • mylopharyngeus (mylohyoid line)
  • glossopharyngeus (lateral wall of tongue – at level of posterior border, last molar)

MIDDLE CONSTRICTOR

• Origin from distal stylohyoid ligament + lesser & greater cornua of hyoid bone
• Ascending and descending fibers (wide raphe)

INFERIOR CONSTRICTOR

• Described in parts based on origin
  • Thyropharyngeus (oblique line, thyroid cartilage + superior margin cricoid)
  • Cricopharyngeus (lateral margins, cricoid cartilage)
    • pars oblique (superficial, upper, into raphe)
    • transverse orientation, tonically constricted
    • pars fundiformis (deep, lower, no raphe)
  • Killian’s dehiscence = between oblique & fundiform parts (at risk of Zenker’s)
    • Some say between thyropharyngeus and cricopharyngeus transverse fibres
    • ABOVE the cricopharyngeus
    • Gateway of teas = most common site of oesophageal perforation
  • Laimer’s triangle = between cricopharyngeus & esophagus (upper circular fibers)
    • BELOW the cricopharyngeus
  • Killian-Jamieson’s area = bilaterally on the sides

HIATUS BETWEEN CONSTRICTORS

• Superior constrictor + occiput =
  • pharyngobasilar fascia + pharyngotympanic tube (cartilaginous) + tensor veli palatini + ascending palatine a.
• Superior + middle constrictor =
  • stylopharyngeus, glossopharyngeal nerve, lingual nerve
• Middle + inferior constrictor
  • thyrohyoid membrane + superior laryngeal nerve + vessels
• Inferior constrictor + esophagus
  • recurrent laryngeal nerve + inferior laryngeal vessels

RELATIONS

• Internal (medial) = palatoglossus, palatopharyngeus, styloglossus, stylohyoid ligament, salpingopharyngeus
• Anterior = oropharynx, base of tongue, epiglottis, larynx
• Posterior = prevertebral fascia & muscles, cervical vertebrae
• Posterolateral = ICA, CN IX/X/XI, IJV, CN XII
• Inferior = continuous into esophagus (with Laimer’s triangle)

ARTERY

• ECA branches – ascending pharyngeal a., facial a. (via tonsillar), superior thyroid a., +/- contribution from inferior thyroid a. (thyrocervical trunk)

VEIN

• Pharyngeal plexus to pterygoid plexus & IJV

NERVE

• pharyngeal plexus

• • motor = pharyngeal branch of vagus, from nucleus ambiguus (cranial accessory via inferior vagal ganglion)
  • sensory = glossopharyngeal + vagus

LYMPH

• Lymph – retropharyngeal (levels II-IV)

  VARIANTS

• Alternative supply of cricopharyngeus by recurrent laryngeal nerve / external branch of superior laryngeal nerve
• Passavant’s ridge/muscle = controversial description as superior constrictor or palatopharyngeus fibers or connective tissue sling